Climate Change

Earth before climate change

Earth with Excess Stratospheric Aerosols

Greenland and the Arctic before melting

Greenland and the Arctic after melting

Climate change represents changes to Earth's temperature and weather patterns. It can be shown in the Intel tab.

Climate change is measured as Global Temperature Anomaly, which starts at +1.3°C. It is caused by Atmospheric Carbon Dioxide above 325.68 ppm, Atmospheric Methane above 1.3 ppm, Atmospheric Nitrous Oxide above 0.29 ppm and Excess Stratospheric Aerosols above 0ppm.

Climate change can be worsened by things such as the Spoils and Economy priorities. It can be improved by using the Environment priority. Certain regions are affected more or less by climate change. Every use of a Strategic Nuclear Barrage increases Excess Stratospheric Aerosols by 0.00777 ppm.

Climate change passively reduces GDP and increases Inequality in every nation, and nations with higher Inequality get hit harder. Extreme climate change can even passively reduce population and Education.

Effects

Nation Effects

Each nation has an ecological vulnerability multiplier, based on its population distribution. Having a large fraction of the population live in ecologically vulnerable regions increases this multiplier, while living in ecologically protected regions decreases this multiplier. Specifically, the ecological vulnerability multiplier of a nation is a number X between 0 and 2, where X calculated as follows:

1. Set X = 0.
2. For each region in the nation, add the population to X if the region is not ecologically protected.
3. For each region in the nation, add the population to X again if the region is ecologically vulnerable.
4. Divide X by the nation's total population.

So if the nation consists of only ecologically protected regions, then its ecological vulnerability multiplier is 0. Whereas if the nation consists of only ecologically vulnerable regions, then its ecological vulnerability multiplier is 2.

Expected Annual GDP % Damage taken by a Nation When Temperature Anomaly = C.
(Capped at 99% Damage.)

Temperature Anomaly Range	GDP % Damage
0 <= C <= 0.25	0
0.25 < C < Max(5.25, 10.25 - Inequality)	(0.14577% × (C - 0.25)^2 + 0.31839% × (C - 0.25)) × 1.14 ^ Inequality
Max(5.25, 10.25 - Inequality) <= C	(0.14577% × (C - 0.25)^2 + 0.31839% × (C - 0.25)) × 1.14 ^ Inequality × Min((C - 0.25 + Inequality)/10, 1.5)
-7 <= C < 0	4.032% × -C
-10.5 <= C < -7	4.032% × -C + 4.032% × (-C - 7)
C < -10.5	4.032% × -C + 4.032% × (-C - 7) + 40.32% × (-C - 10.5)

The Expected Annual GDP % Damage that a nation would take is then multiplied by the nation's Ecological Vulnerability Multiplier, and once again capped at 99%. This is how much GDP % Damage the nation would take each year, but is applied in monthly penalties.

For example, if a nation is supposed to lose 46% of its GDP each year, then the game applies a penalty of roughly 5% GDP every month. Because (100% - 5%)^12 = roughly 54% = 100% - 46%.

The damage done to a nation's Inequality is equal to 1/5th of its GDP % damage. So in the previous example where the nation loses 5% GDP each month, the nation also gains 5% / 5 = 0.01 Inequality each month.

At extreme levels of climate change, the nation suffers two additional penalties every month: - If the atmospheric CO2 > 945ppm and the nation's Education > 9.45, then the nation loses Min((CO2_ppm - 945) * 0.005, 0.1) Education. - If the temperature anomaly is more than 8 points away from 0, then all regions suffer population growth penalties of roughly 1% per degree further away from 0. This penalty is also affected by ecological vulnerability, but ecological protection only provides half the benefit.

Event Effects

As long as Global Temperature Anomaly is above or below a certain value it will cause regular negative events.

Event	Global Temperature Anomaly	Effects
Global Crop Failures	-4°C	All nations will lose -50% GDP, -6 Cohesion and up to -33% Population.
Arctic Methane Eruption	+1.25°C	Atmospheric Methane increases by 0.05 ppm. Factions can choose to pay 100 Money and 20 Ops to gain 250 Research.
Environmental Degradation	+1.5°C	A random nation will lose GDP and gain Inequality and Unrest while the faction controlling it will lose Public Opinion. The Unrest can be canceled and Public Opinion increased by paying Money. The Initiative can instead gain some Money but this will reduce Education by -1 and increase Inequality by 1.
Wet Bulb Disaster	+1.5°C	A random nation will lose Population. If a faction is controlling it, it can pay 100 Money and 20 Ops to reduce the Population loss and gain Public opinion.

Global Sea Level Anomaly

Global Sea Level Anomaly starts at +24cm. Every month, it rises by another 0.017cm × the Global Temperature Anomaly, if the Global Temperature Anomaly is more than 0.

There are also 10 glaciers, basins and shelves that may melt if climate change is not stopped, most of them increasing Global Sea Level Anomaly. Once Global Sea Level Anomaly rises above +60cm it will become visible and start causing negative effects.

Event	Global Temperature Anomaly	Sea Level Rise
Larsen A Ice Shelf Collapses	+0.4°C	0cm
Larsen B Ice Shelf Collapses	+0.55°C	0cm
Larsen C Ice Shelf Collapses	+0.94°C	5cm
Thwaits Ice Shelf Collapses	+1.35°C	10cm
Pine Island Glacier Collapses	+1.8°C	20cm
Greenland Melt Accelerates	+2.2°C	120cm
Totten Ice Shelf Collapses	+2.7°C	10cm
Aurora Basin Ice Retreats	+3.8°C	20cm
Wilkes Basin Retreats	+4.2°C	120cm
Western Antarctic Ice Sheet Collapsing	+4.8°C	50cm

Note that Sea levels can never go down within the time scales of the game. Ice that has melted into the ocean cannot simply teleport itself back on to the continent, even if the Global Temperature Anomaly has been reduced. So events caused by high sea levels can only be avoided by fixing the Climate quickly, before the sea levels rise too far.

Temperature Anomaly Sources

The Global Temperature Anomaly is simply calculated as the sum of the following:

Component	Base ppm	°C Change Per Excess ppm	Min °C	Max °C
CO2	325.68	1 / 94.5	0	None
CH4	1.3	21 / 94.5	0	None
N2O	0.29	289 / 94.5	0	None
Aerosols	0	-1 / 0.03885	-40	0

Greenhouse Gas (GHG) Sources

Methods of changing the amount of greenhouse gases in the atmosphere include but are not limited to:

Source	Frequency	Shared Multiplier	CO2	CH4	N2O
Natural Removal	Every Month	None	CO2 / -90000	CH4 / -144	N2O / -14641
Xenoflora	Every Month	Average Xenoflora Growth Levels Per Region / 100	-0.2875	0	0
Arctic Methane Eruption	At most once every 8 months	None	0	0.04 to 0.06	0
Nations	Every Month	Pollution Multiplier / 12 × (GDP in billions × 275000 + Population × 2.41 × Min(1,GDPPC/15000)^2 × Min(1,GDPPC/7500)^2 + Min(Oil Regions × 250000000, GDP in billions × 27500))	0.3292	0.115 / 21	0.062 / 289
Spoils Priority	Every Completion	Pollution Multiplier / (Population / 50 million) ^ 0.35 × (GDP in billions) ^ 0.35 / 1000000 × (1 + 0.5 per Resource Region)	6.124	0.832	0.2
Environment Priority at 10 Sustainability	Every Completion	(Population / 50 million) ^ 0.35 / 10000	-4.758325	-0.033275	-0.03025

Note: These Environment Priority pollution removal values include the bonuses from the technologies Clean Energy, Climate Change Mitigation, Designer Lifeforms, and Integrated Earth-Space Economy, because it is impossible to reach Sustainability 10 in any nation before researching these technologies.

Aerosol (GHG) Sources

Methods of changing the amount of aerosols in the atmosphere include but are not limited to:

Source	Frequency	Aerosols Added (ppm)
Natural Removal	Every Month	Max(Aerosols * 0.935f - 0.001f, 0f) - Aerosols
Region Nuked	Every Nuke	0.00777 * Region Area (km2) / 10000 if Region is an Island smaller than 10000km2.
		0.00777 Otherwise
Nuclear Program Completion	Every Completion	0.0000777
Volcano Eruption	At most once every 6 years	0.008 to 0.012
Major Volcano Eruption	At most once every 50 years	0.016 to 0.024
Colossal Volcano Eruption	At most once per Campaign	0.04 to 0.06